Nomogram-Based Prediction Model for Postherpetic Neuralgia in Immunosuppressive Patients

Background/Objectives: Herpes zoster is caused by varicella-zoster virus reactivation, which often leads to a chronic pain condition named postherpetic neuralgia (PHN). Patients with immunosuppressive conditions face a heightened risk of developing PHN. This study aims to identify factors contributing to PHN development in immunosuppressive patients. Methods: This retrospective cohort study was conducted involving 219 immunosuppressive patients from two centers and split into training and test cohorts. Participants were divided into PHN (n = 88) and acute phase pain (ACP, n = 131) groups. Univariate and multivariate logistic regression analyses were used to identify clinical predictors of PHN. A nomogram was constructed to predict PHN risk by integrating significant predictors. The discrimination, calibration and clinical usefulness of the nomogram were evaluated. Results: Multivariate analysis revealed metabolic syndrome, older age, higher lactate dehydrogenase (LDH), and higher neutrophil-to-lymphocyte ratio (NLR) as significant PHN predictors. The nomogram showed good discrimination in both training (AUC of 0.83 [95% CI 0.77–0.90] with a specificity of 0.78, sensitivity of 0.87, NPV of 0.90, and PPV of 0.73) and test cohorts (AUC of 0.85 [95% CI 0.75–0.96] with a specificity of 0.82, sensitivity of 0.85, NPV of 0.89, and PPV of 0.76). Clinical decision curve analysis confirmed the practical utility of the nomogram. Conclusions: The nomogram incorporating age, metabolic syndrome, LDH, and NLR are useful in estimating PHN risk among immunosuppressed patients.